This invention relates to a process and an apparatus for the production of a flowable reaction mixture which can react to form a plastic material, and particularly a polyurethane material. The process is characterized in that at least two flowable reaction components are guided from supply zones as main flows, and are metered in a predetermined ratio to several mixing zones which are connected in parallel.
It is known (German Auslegeschrift No. 1,114,313 corresponding to U.S. Pat. No. 3,073,533), that it is possible to foam into the corners of refrigerators simultaneously using four mixing heads. The components can be supplied to these mixing heads either by use of a central pump station or by separate pumps and control relays for each mixing head. Thus, in the first embodiment, one pump per component is allocated to each mixing head, and the central pump station has a common drive for the pumps. In the second embodiment, the individual pumps are driven separately. However, the expense in terms of apparatus is considerable. More importantly, the area surrounding the mold can only be reached with difficulty due to the large apparatus and to the plurality of pipelines and tube-lines leading to the mixing heads. This necessarily means that operating staff are hindered in their work. The great spatial requirement is also a disadvantage.
In order to avoid this expense, a distributing pipe system has been inserted into the cavity provided for the foam core during the production of motor vehicle underbodies (U.S. Pat. No. 3,415,568) consisting of two shells enclosing a foam core. This system is connected to a single mixing head and has several outlets at desired points. This distributing pipe system remains in the foam core and simultaneously serves as a reinforcing insert. This method cannot be used in the case of thin-walled moldings, and many moldings do not require a reinforcing insert.
An object of the present invention is to provide a process and an apparatus which may be used to fill cavities, and in particular to fill molds having a high charging capacity with a low flow front speed. Additionally, the surroundings of the filling point or of the molds are occupied by only a few compact parts so that a good accessibility is provided.